Earnings per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Numerator:
Net income attributable to Stewart	$ 29,434	$ 88,663	$ 148,991	$ 237,718
Denominator (000):
Basic average shares outstanding (in shares)	27,113	26,873	27,031	26,803
Diluted average shares outstanding (in shares)	27,371	27,238	27,359	27,090
Basic earnings per share attributable to Stewart (in usd per share)	$ 1.09	$ 3.30	$ 5.51	$ 8.87
Diluted earnings per share attributable to Stewart (in usd per share)	$ 1.08	$ 3.26	$ 5.45	$ 8.78
Stock options
Denominator (000):
Average number of dilutive shares relating to options and grants of restricted shares and units (in shares)	124	190	181	160
Restricted stock and restricted stock units
Denominator (000):
Average number of dilutive shares relating to options and grants of restricted shares and units (in shares)	134	175	147	127